GB2300886A - Reversible flow turbine - Google Patents

Abstract

An axial flow turbine is provided with radially extending blades that can pivot or flex about one edge, so that the direction of rotation of the turbine is constant despite reversal of the flow in relation thereto. In one form (figs. 1, 2) the blades are formed from sheet material and are connected to a hub portion 7 by a neck 9. The turbine is mounted on a handle (5) and functions as a toy. Alternatively, the blades are pivotally mounted on arms (24, 43) (figs. 3 to 9) and the turbine may function as a hydraulic turbine for a tidal barrage, or as part of a toy incorporating visual effects, with or without a battery operated light.

Description

"Improvements in or relatina to Turbines" This invention relates to turbines.

A propeller turbine comprises a bladed impeller rotatable in an air or water flow parallel to the axis of rotation of the impeller. In such a turbine the blades are canted relative to the flow direction, in the manner of a ship's propeller, so as to optimise the rotation of the impeller in one direction, that is in a clockwise direction or an anti-clockwise direction, by means of the air or water flowing in the required sense along the flow direction. It is known for the blades of such an impeller to be adjustable so that their angles relative to the flow direction can be controlled in dependence on the flow rate through the turbine in order to obtain high efficiency.

However, if the sense of flow of air or water through such a turbine is reversed so that the air or water passes through the turbine in the opposite sense to that for which the turbine is designed, the impeller will be caused to rotate in the opposite direction, so that, if the turbine is to be used for driving a generator for example, drive will not be imparted to the generator in the required direction unless the drive train incorporates special gearing for reversing the drive direction.

It is an object of the invention to provide an improved turbine for use in a variety of applications in which it is desirable that the direction of flow through the turbine is reversible.

According to the present invention there is provided a turbine comprising an axial spindle and a bladed impeller mounted on the spindle and rotatable about an axis of rotation passing through the spindle by means of fluid flow in a direction parallel to said axis of rotation, wherein the impeller comprises an axial portion attached to the spindle and radially extending blades connected to the axial portion and capable of limited angular displacement about corresponding radial axes in response to a change in the sense of the fluid flow so that, when the fluid flow is in one sense parallel to said axis of rotation, the blades adopt a first blade angle causing the impeller to be rotated in one direction and, when the fluid flow is in the opposite sense parallel to said axis of rotation, the blades adopt a second blade angle causing the impeller to be rotated in the same direction as the impeller is rotated by the fluid flow in said one sense.

Thus, regardless of the sense of the fluid flow, the impeller is always rotated in the same direction, and no special measures are required to reverse the direction of drive if the turbine is coupled to drive a generator, for example. It is possible to conceive of many applications in which such a reversible flow turbine could be used.

For example, if the turbine is to be used in a tidal barrage for imparting drive to a generator from the tidal water flow, a duct may be provided for flow of water in either sense along the duct, the impeller being mounted coaxially within the duct so as to be rotatable in said one direction by flow of water in either sense along the duct.

In another application, in which the turbine may be used as a child's toy for example, the spindle may be mounted on a handle extending transversely to the axis of rotation, the impeller being rotatable in said one direction by air flow as the handle is moved so as to cause the impeller to move backwards and forwards along the axis of rotation. Since such backward and forward movement will continue to cause the impeller to rotate in the same direction, even though the direction of air flow relative to the impeller will change each time that the direction of movement is changed, this will cause the impeller to rotate continuously in a pleasing way. If required the attractive appearance of the rotating impeller can be enhanced by having brightly coloured blades.

In a particularly simple and inexpensive version, the axial portion and the blades of the impeller may be integrally formed from a single sheet of material, and the blades may be joined to the axial portion by parts of the sheet which are sufficiently flexible to permit limited angular displacement of the blades about their corresponding radial axes in response to a change in the sense of the fluid flow. For example each said part may be constituted by a neck joining the associated blade to the axial portion and defined by a slot extending part of the way around the axial portion between the axial portion and the blade.

Preferably the arrangement is such that the first and second blade angles are symmetrically located with respect to the median plane which is orthogonal to said axis of rotation.

In one embodiment of the invention the impeller includes radially extending arms connected to the axial portion, the blades being connected to the arms to permit limited angular displacement of the blades on the shafts.

Each blade may comprise a bush portion through which the associated arm extends, and a main portion joined to the bush portion and extending circumferentially to a point adjacent to the bush portion of the next adjacent blade.

It is preferred in such an arrangement that the bush portion of each blade includes a formation which engages a first stop on the associated arm when the blade adopts the first blade angle and which engages a second stop on the arm when the blade adopts the second blade angle.

Where the turbine is to be used as a child's toy, the impeller may be mounted so as to be rotatable relative to a body, and the axial portion may include a viewing window through which a brightly coloured pattern on the body is viewable as the impeller rotates. The viewing window may be a complex lens intended to provide a series of images of the pattern.

Furthermore the body may incorporate a light which may be powered by a battery or by a generator driven by the turbine, and which may serve to illuminate the pattern.

In order that the invention may be more fully understood, a number of embodiments of the turbine in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figures 1 and 2 show a sectional view and a front view of a first embodiment; Figures 3, 4 and 5 show a front view and two side views of a second embodiment; and Figures 6, 7, 8 and 9 show a front view, a sectional view and two side views of a third embodiment.

Referring to the first embodiment of Figures 1 and 2, the turbine 1 comprises an impeller 2 fixedly mounted on a spindle 3 extending through a tube 4 attached to one end of a handle 5 so that the impeller 2 is freely rotatable about an axis of rotation 6. The impeller 2 is formed from a single sheet of card or other flexible material and comprises an axial portion 7 and four blades 8, the blades 8 being connected to the axial portion 7 by neck parts 9 defined by circumferential slots 11 extending part of the way around the axial portion 7 and joined to radial slots 10 between the blades 8.

The turbine 1 may be moved backwards and forwards in the direction of the arrows 12 in Figure 1 by means of the handle 5, and this causes the resulting air flow acting on the impeller blades 8 to flex the trailing portion of each blade 8 out of the median plane of the impeller 2, as shown by the broken lines 13 and 14 in Figure 1. The direction of flexing is opposite to the direction in which the turbine is moved, and the degree of flexing will be the same for the same degree of movement in each direction.

Thus the blades 8 are angled at all times in such a manner that the air flow acting on the blades 8 causes the impeller 2 to be rotated in the same direction, as shown by the arrow 15 in Figure 2. The impeller 2 may be patterned on one or both sides so as to provide an attractive appearance when rotating, and in addition may include a logo.

The second embodiment of turbine shown in Figures 3, 4 and 5 is intended to be mounted within a duct (not shown) for flow of water in a tidal barrier. The turbine 20 comprises an impeller 21 mounted on a shaft 22 for applying rotary drive to a drive train coupled to a generator (not shown). The impeller 21 incorporates an axial hub portion 23 and four arms 24 extending radially outwardly from the hub portion 23. In addition the impeller 21 has four blades 25 connected to the arms 24 by bush portions 26 so that in each case the blade 25 extends circumferentially to a point adjacent to the bush portion 26 of the next blade and is capable of limited angular displacement about the arm 24. The angular displacement of each blade 25 is limited by two stops 27 and 28 (see Figure 3) provided on the associated arm 24 and engageable by a formation (not shown) on the bush portion 26.

When the direction of water flow along the duct is as shown by the arrow 29 in Figure 4 the blades 25 are angularly displaced in one direction, whereas, when the direction of water flow along the duct is as shown by the arrow 30 in Figure 5 due to a change in the tide, the blades 25 are angularly displaced in the opposite direction. Thus, regardless of the direction of water flow, the impeller 21 is at all times rotated in the one direction shown by the arrow 31 in Figure 3 so as to drive the generator in the same direction at all times.

The third embodiment shown in Figures 6, 7, 8 and 9 is intended for use as a child's toy. In this case the turbine 40 comprises an impeller 41 having an axial hub portion 42, four radially extending arms 43 and four blades 44 joined to the arms 43 by bush portions 45 so as to be capable of limited angular displacement relative thereto.

The general construction and operation of the impeller 41 is similar to that of the impeller 21 of the second embodiment and will therefore not be described in detail.

As will be seen more particularly by referring to the sectional view of Figure 7, the axial portion 42 of the impeller 41 is mounted on a moulded plastics body 45 by an integral stub axle 46 extending through a bearing bush 47 and held therein by a bolt 48. The bearing bush 47 is surrounded by an annular flange 49 which is a snap fit within the body 45. In addition the body 45 is provided with an end cover 50 which is attached to the remainder of the body 45, by sonic welding for example, after attachment of the impeller 41 to the body 45. The body 45 is also provided with an integral handle 51 and optionally includes a detachable holder 52 for batteries for powering a light 53.

The axial hub portion 42 of the impeller 41 may incorporate a transparent plastics viewing window through which a pattern provided on the annular flange 49 for example may be viewable. The pattern is brightly coloured and preferably also reflective so as to prevent an attractive appearance when viewed through the viewing window. The viewing window may be a multi-faceted lens so as to provide a series of images of the pattern which change as the impeller 41 rotates so as to produce an intricate and changing total pattern which may be back lit by the light 53. In a variant of this embodiment the lens is adapted to project such images onto an external surface, such as a surrounding wall surface. In another variant the viewing window may be in the form of a series of circumferentially spaced apertures in an opaque surface so that the pattern, which may be a logo, is revealed only when the impeller is rotating.

Figures 8 and 9 show the positions of the blades 44 as the turbine 40 is moved backwards and forwards by the handle 51 so as to cause the impeller 41 to rotate continuously in the same direction.

Claims (14)

1. A turbine comprising an axial spindle and a bladed impeller mounted on the spindle and rotatable about an axis of rotation passing through the spindle by means of fluid flow in a direction parallel to said axis of rotation, wherein the impeller comprises an axial portion attached to the spindle and radially extending blades connected to the axial portion and capable of limited angular displacement about corresponding radial axes in response to a change in the sense of the fluid flow so that, when the fluid flow is in one sense parallel to said axis of rotation, the blades adopt a first blade angle causing the impeller to be rotated in one direction and, when the fluid flow is in the opposite sense parallel to said axis of rotation, the blades adopt a second blade angle causing the impeller to be rotated in the same direction as the impeller is rotated by the fluid flow in said one sense.

2. A turbine according to claim 1, which is intended to be used in a tidal barrage for imparting drive to a generator from the tidal water flow, wherein a duct is provided for flow of water in either sense along the duct, the impeller being mounted coaxially within the duct so as to be rotatable in said one direction by flow of water in either sense along the duct.

3. A turbine according to claim 1, wherein the spindle is mounted on a handle extending transversely to the axis of rotation, the impeller being rotatable in said one direction by air flow as the handle is moved so as to cause the impeller to move backwards and forwards along the axis of rotation.

4. A turbine according to claim 1, 2 or 3, wherein the axial portion and the blades of the impeller are integrally formed from a single sheet of material.

5. A turbine according to claim 4, wherein the blades are joined to the axial portion by parts of the sheet which are sufficiently flexible to permit limited angular displacement of the blades about their corresponding radial axes in response to a change in the sense of the fluid flow.

6. A turbine according to claim 5, wherein each said part is constituted by a neck joining the associated blade to the axial portion and defined by a slot extending part of the way around the axial portion between the axial portion and the blade.

7. A turbine according to any preceding claim, wherein the first and second blade angles are symmetrically located with respect to the median plane which is orthogonal to said axis of rotation.

8. A turbine according to any preceding claim, wherein the impeller includes radially extending arms connected to the axial portion, the blades being connected to the arms to permit limited angular displacement of the blades on the shafts.

9. A turbine according to claim 8, wherein each blade comprises a bush portion through which the associated arm extends, and a main portion joined to the bush portion and extending circumferentially to a point adjacent to the bush portion of the next adjacent blade.

10. A turbine according to claim 9, wherein the bush portion of each blade includes a formation which engages a first stop on the associated arm when the blade adopts the first blade angle and which engages a second stop on the arm when the blade adopts the second blade angle.

11. A turbine according to any preceding claim, wherein the impeller is mounted so as to be rotatable relative to a body, and the axial portion includes a viewing window through which a brightly coloured pattern on the body is viewable as the impeller rotates.

12. A turbine according to claim 11, wherein the viewing window is a complex lens intended to provide a series of images of the pattern.

13. A turbine according to claim 11 or 12, wherein the body incorporates a light which may be powered by a battery or by a generator driven by the turbine, and which may serve to illuminate the pattern.

14. A turbine substantially as hereinbefore described with reference to the accompanying drawings.